I. Field of the Invention
The present invention relates generally to fluid filtering devices and, more particularly, to an inline fluid filtering device with a filter element bypass means.
II. Description of the Prior Art
There are, of course, a number of previously known fluid filtering devices which are adapted for connection in series with a fluid line in a fluid system. Such a fluid system can, for example, comprise a hydraulic system in which the fluid filtering device is connected to either the suction line from a hydraulic reservoir and to the hydraulic pump or the return line from the hydraulic system into the fluid reservoir. In either case, it is necessary to maintain fluid flow through the filtering device in order to prevent pump cavitation, loss of system efficiency or even damage to the hydraulic system.
It is well known in the art of fluid filtering devices that as a filter element becomes increasingly clogged with debris, the pressure drop across the filter element likewise increases and diminishes the outward flow from the filter element. As the decreasing fluid flow becomes excessive, it can cause one or more of the aforementioned problems.
In order to protect the hydraulic or other fluid system from reduced fluid flow resulting from a clogged filter element, many previously known filtering devices include bypass means for bypassing the fluid flow around the filter element at a predetermined pressure drop across the filter element which is indicative of excess filter clogging. These previously known filter devices with bypass means, however, are disadvantageous in several different respects.
One disadvantage of these previously known bypass valves is that such valves are oftentimes complex in construction and are constructed from a multiplicity of separate components. The complexity of these previously known bypass valves not only increases the initial construction or manufacturing cost of such valves, but, in addition, such bypass valves are prone to failure since failure of any one of the numerous bypass valve components can render the entire bypass valve inoperable.
Moreover, many of these previously known bypass valves simply comprise a circular valve member urged against a valve seat by helical spring or other conventional resilient means. The valve member, which is of a relatively small area, forms the entire pressure sensing means and, due to its relatively small size, the bypass valve member opens only slightly and somewhat spasmatically. Consequently, the fluid flow through the filter device, even with the bypass valve in its open position, is often at a lower than desired flow rate.
A still further disadvantage of these previously known bypass valves is that such valves are typically secured directly to and within the housing for the fluid device. Consequently, when maintenance and/or cleaning of the bypass valve assembly is required, time consuming disassembly of virtually the entire fluid filtering device is usually required. Such disassembly of the fluid filtering device also results in expensive and prolonged downtime for the hydraulic, or other fluid, system.
A still further disadvantage of these previously known filter devices with bypass valve means is that the main housing for the fluid filtering device is of complex, and therefore, expensive construction. Moreover, many of these devices are not readily suitable for direct connection with a fluid line but instead require modification of the fluid system and the fluid fittings in order to accommodate the fluid filter device. Lastly, these previously known fluid filtering devices also require the use of baffles within the device main housing in order to insure a uniformly distributed fluid flow through the filter element. Such baffles also increase the complexity and cost of the main housing.